ᐅ Ground-source heat pump with or without controlled mechanical ventilation

Created on: 22 Dec 2016 22:19
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nautilus
Hello everyone,
we have received a cost estimate from the architect for a KfW 70 house, including a mechanical ventilation system with heat recovery. When I asked about KfW 55, the architect said that if you go with a ventilation system without heat recovery and add about €8000 (approximately $8,700) extra, then you could have a geothermal heat pump (deep probe). That would probably make KfW 55 achievable. Walls and everything else are planned according to the KfW 55 standard. He said it doesn’t make sense to use heat recovery with geothermal energy because supposedly there are no savings from it. The ventilation would then be €6000 (about $6,500) cheaper. I have to say I’m confused and don’t understand what he means. Can someone explain what he means?
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Alex85
23 Dec 2016 13:12
In a controlled ventilation system with heat recovery, the outdoor air is preheated, whereas in a standard ventilation system it is not.
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nautilus
23 Dec 2016 13:22
That basically means that a higher heating capacity is necessary to achieve the same level of comfort. To me, this just represents a cost factor that differs between the two systems, or am I mistaken?
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oleda222
23 Dec 2016 13:47
That's true, if you sit by an open window at minus 5 degrees Celsius (23°F), you just need to turn up the heating a bit, and then you don’t notice the cold air anymore.
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nautilus
23 Dec 2016 14:06
That's exactly the point. I am well aware that such behavior is not environmentally conscious. However, I would not categorize this aspect under comfort. Let me try to put it differently: Are there any other advantages of a ventilation system with heat recovery, besides recovering heat, compared to a system without heat recovery?
Mycraft23 Dec 2016 14:09
nautilus schrieb:
He said that using heat recovery with geothermal heating doesn’t make sense because supposedly there are no savings.

Sorry, but that is complete nonsense... the architect should probably educate himself before making such statements.

The advantage is obvious... the heat stays inside the house, so the heat generator (whether it’s oil, gas, air, ground, etc.) needs to heat less...

Which, of course, has a positive effect on your wallet.
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oleda222
23 Dec 2016 14:48
nautilus schrieb:
That’s exactly the point. I understand that such behavior is not environmentally friendly. However, I wouldn’t categorize this aspect under comfort. Let me try to rephrase: Are there any benefits of a ventilation system with heat recovery beyond recovering heat, compared to a system without heat recovery?

Please try sitting in front of an open window at -5°C (23°F). Do you seriously think that turning up the heating can compensate for the loss of comfort caused by the open window?

There is a draft, it’s cold, and you might catch a cold, etc. With a mechanical ventilation system with heat recovery, the air exchange rate is lower, which reduces this effect.

But very cold air still comes into the house.

My post was meant to be ironic...

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